Controllers for brushless motors: E-bikes require high initial torque and therefore models that use brushless motors typically have Hall sensor commutation for speed and angle measurement. An electronic controller provides assistance as a function of the sensor inputs, the vehicle speed and the required force. The controllers generally allow input by means of potentiometer or Hall Effect twist grip (or thumb-operated lever throttle), closed-loop speed control for precise speed regulation, protection logic for over-voltage, over-current and thermal protection. Bikes with a pedal assist function typically have a disc on the crank shaft featuring a ring of magnets coupled with a Hall sensor giving rise to a series of pulses, the frequency of which is proportional to pedaling speed. The controller uses pulse width modulation to regulate the power to the motor. Sometimes support is provided for regenerative braking but infrequent braking and the low mass of bicycles limits recovered energy. An implementation is described in an application note for a 200 W, 24 V Brushless DC (BLDC) motor.
Historically, women's bicycle frames had a top tube that connected in the middle of the seat tube instead of the top, resulting in a lower standover height at the expense of compromised structural integrity, since this places a strong bending load in the seat tube, and bicycle frame members are typically weak in bending. This design, referred to as a step-through frame or as an open frame, allows the rider to mount and dismount in a dignified way while wearing a skirt or dress. While some women's bicycles continue to use this frame style, there is also a variation, the mixte, which splits the top tube laterally into two thinner top tubes that bypass the seat tube on each side and connect to the rear fork ends. The ease of stepping through is also appreciated by those with limited flexibility or other joint problems. Because of its persistent image as a "women's" bicycle, step-through frames are not common for larger frames.
As the managing editor of Ars Technica, one of my duties is to monitor the daily torrent of news tips and PR emails. The overwhelming majority of them is deleted after a glance, and the news tips and story ideas are passed along to the appropriate writer. Sometimes a product announcement will catch my eye, and I will follow up. Once in a blue moon, I'll say, "please send me one so that I may review it." And that's how I ended up riding an electric bike around the Chicago suburbs for two weeks.
DON'T BUY THIS BIKE!!!!! Worst customer service ever!!! I bought this bike for my 18 year old son to commute to school. It worked well for the first 2 months but the battery is cheap and stated to wear out. I tried going on the website, but they battery shows as out of stock, and has been for 3 months now. I left 5 emails with customer service, never got a reply. Also there is no number listed on their website to even speak to a real person. Now I have a worthless 5 month old bike..... horrible this company should be ashamed.
Simple, convenient, cheap, and economical—bicycles are one of the world's favorite forms of transportation. But they're not for everyone. They can be hard to pedal up and down hills or with heavy loads, and elderly or disabled people may find them impossible to manage. In the last few years, a new generation of electric bicycles has begun to revolutionize our idea of environmentally friendly transportation. These new cycles have all the convenience of cars with all the simple economy of ordinary cycles. Let's take a closer look at how they work.